Lapping machines are common for producing read-write heads, or sliders, for disc drives. An example of a commercially available row bar lapping machine is the “Optium ASL 200 Lapping System” from Veeco Instruments. A row bar lapping machine, sometimes alternately referred to as a row or bar lapping machine, requires very accurate and precise control of the pitch angle of the bar during the polishing process. The bar must be allowed to move downward as material is lapped from the bar without affecting the pitch angle, and if the bar is lifted up off the platen, it must be done without disturbing the pitch angle.
Precise linear bearings allow for the necessary vertical motion for the lapping head and thereon mounted bar, but they do not meet the stiffness requirements. Conventional parallelogram flexure assemblies, which allow precise translation without rotation, may be acceptable for pitch control, but are usually large in size and expensive.
Conventional parallelogram flexures include a “web” formed from a single piece of metal, usually formed by electrical discharge machining (EDM). The EDM process generally limits the horizontal webs to no less than 0.015 inch thick. Because the actuation force to move the flexure vertically is proportional to the cube of the horizontal web thickness, in order to keep the actuation force manageable, it is desired to have the horizontal webs as thin as possible. Unfortunately, it is difficult with EDM to make the webs sufficiently thin. Even if EDM-made webs were sufficiently thin, the cost of the EDM process may be cost prohibitive.
Improved flexure designs are desired.